Atomic hydrogen density measurements in the Tara tandem mirror experiment

• Published in: Physics of fluids. B, Plasma physics Plasma physics, 1990-09, Vol.2 (9), p.2168-2172
• Main Authors: Guss, W. C., Yao, X. Z., Pócs, L., Mahon, R., Casey, J., Horne, S., Lane, B., Post, R. S., Torti, R. P.
• Format: Article
• Language: English
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 700102 - Fusion Energy- Plasma Research- Diagnostics; DENSITY; ELECTRON TEMPERATURE; ELEMENTS; EMISSION; Exact sciences and technology; HYDROGEN; INELASTIC SCATTERING; ION TEMPERATURE; MAGNETIC MIRRORS; MEASURING INSTRUMENTS; NONMETALS; OPEN PLASMA DEVICES; PHYSICAL PROPERTIES; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; PLASMA DENSITY; Plasma diagnostic techniques and instrumentation; PLASMA DIAGNOSTICS; PLASMA PRESSURE; RADIATION DETECTORS; SCATTERING; SECONDARY EMISSION; TANDEM MIRRORS; TARA DEVICES; TEMPERATURE DISTRIBUTION; THERMONUCLEAR DEVICES; THOMSON SCATTERING
• ISSN: 0899-8221; 2163-503X
• DOI: 10.1063/1.859438

Neutral and plasma density have been measured in the north well of the central cell of the Tara tandem mirror [Nucl. Fusion 2 2, 549 (1982)]. The electron plasma density and temperature on the magnetic axis were measured by Thomson scattering to be about 3×1012 cm−3 and 70 eV, respectively. The corresponding axial neutral hydrogen density was found to be 1 ×109 cm−3, while near the plasma edge at r=15 cm it reached 1×1010 cm−3. The fill gas density at r≥22.5 cm was ≊1011 cm−3. Additional information from secondary electron detectors was used to estimate the radial ion temperature distribution, which was found to have about the same width, 12 cm, as the plasma density. The resulting ion pressure profile is peaked compared to the electron pressure profile. Charge exchange losses in the well are found to have a maximum at a radius equal to half the e‐folding distance of the plasma density and ion temperature distributions.